It is well known to utilize various composite fabrics which are in part or totally disposable after use. Garments, linens, drapes, towels and other useful articles provided as a composite for medical use and chemical use are available. Regarding hospital and medical use, disposables and reusable fabrics and composites are used to face the considerable quantities of infectious material medical waste in primary and acute care facilities. One of the principle reasons why medical and other facilities have turned to disposables is that reusables suffer from one physical property or another, specifically reusables cannot readily provide liquid barrier properties especially after the initial two or three laundry cycles.
Although there is clearly a benefit in the use of disposables in the medical arts by avoiding the necessity of human contact with medical waste in cleaning reusables, nonbiodegradable disposals are posing a problem which is only now being recognized. Landfill sites are becoming increasingly burdened with disposables which do not biodegrade for decades. As landfill sites become fully exploited, new sites must be found which are rightfully opposed by residents located proximate to the proposed site locations. In addition, incineration fails to be a viable alternative. Waste disposal incinerators are wholly inadequate. In addition these same disposable problems exist and possibly even more serious regarding hazardous chemical suits and wear.
One of the requirements for obtaining safe working conditions for employees in various industries other than medical or emergency service organizations is the provision of protective garments that prevent toxic chemicals or other contaminants from coming into contact with the worker's body. The need for such protection has been emphasized in recent years by enactment of local, state and federal laws and/or regulations requiring the use of protective garments under many circumstances.
Various types of materials have been used for chemical barrier applications including polymeric films, rubber-based sheet material and multilayered composites made by bonding of film layers to one another or to fabric. While the available materials may provide an effective barrier to some types of chemicals, none are known to prevent permeation of all hazardous chemicals. One polymeric film material, for example, is effective for primary alcohols and inorganics mineral acids, but not for saturated hydrocarbons and chlorinated olefins. Another material is effective for many types of chemicals, but not for organic solvent compounds or heterocyclic ethers. Such gaps in coverage require careful selection of the protective material for its end use environment. In many instances, the specific chemical components in a contaminating mixture, as may be present in waste cites and hazardous response situations, may be unknown so that selection of particular contaminants is not feasible. A need thus exists for a barrier material effective for a wide range of chemicals even beyond those currently being utilized.
The migration of chemicals through a complex laminated material involves a sequence of process steps including adsorption, diffusion and desorption, the combination of which is defined as permeation. There are a number of factors which influence the rates that each of these process steps will occur, or whether each step will occur at all. The various factors which govern the permeation rates include degradation of the laminate by the chemical, temperature, pressure, thickness, solubility, stereo chemistry, concentration, state, vapor pressure, viscosity and the like. If the chemical from which protection is sought is a liquid the rate limiting step becomes diffusion in the adsorption and desorption effects can be neglected. Diffusion under ideal circumstances is governed by the solubility of the chemical and the protective material relative to each other.
A continuing need for protective garments with low permeability, i.e. long break through time and a low permeation rate, for various chemical compounds or mixtures of compounds. The polymer membranes and laminates used in protective wear such as gloves, coverall suits, hoods, boots and the like, for use in a work environment or in a home or in an emergency spill environment must protect against chemical compounds or mixtures thereof which are hazardous to health. Such compounds can include organic solvents, paints, varnishes, glues, cleaning agents, degreasing agents, drilling fluids, epoxy materials, and the like. Permeation studies have surprisingly shown that the break through time is often less than half an hour, sometimes only a few minutes or less. The studies have also shown the break through time and a permeation rate is to a great extent depended upon the combination of the hazardous substance and the material for protective clothing. In view of the foregoing, it is quite obvious that a great need exists for protective garments featuring polymer membranes without the aforementioned disadvantages. Unfortunately, no method of selecting suitable combinations other than the method of trial and error has been proposed; however, certain stand alone film membranes or sheet materials have chemically been diagnosed as having resistance to specific chemicals. One of these membranes or sheet materials can be constructed of polyvinyl alcohols and various copolymers of polyvinyl alcohols. In addition, polyvinyl alcohol polymer sheet materials can be readily soluble in water. This solubility in water can be adjusted by additives to the polyvinyl alcohol and various other treatments which can elevate the water temperature of solubility of the polyvinyl alcohol to temperatures higher than normal use, i.e. 130.degree.-150.degree. F. and above. A totally water soluble polymer sheet material could be most useful in meeting disposable requirements of state, federal and local governments and such materials can be readily applied to an existing chemical protection suit and desorbed from the surface of the suit in the field after use by hot water washing.